Lifting jack



July 28, 1931. E. J. VAN FLEET 1,816,625 l Y LIFTING JACK Fi1 ed April 21,. 1924 2 Sheets-Sheet l July 2s, 1931.

E. J. VAN FLEET LIFTING JACK Filed April 21., 1924 2 sheets-sheet 2 7m-J, Wwf@ @i Patented July 28, 1931 UNITED STATES PATENT OFFICE vELON J. VAN FLEET, JOLIET, ILLINOIS, ASSIGNOR TO WILLIf-.M E. PRATT, OF

. CHICAGO,

ILLINOIS y l LiF'rrNG .Tacx

Application filed April 21,

`1o mechanism for raising and lowering the plunger o r supporting member of the jack. Another object is to provide a jack comprising a rack bar adapted to be raised and lowered bya pivoted lever which carries a pawl andfa detent connected by a spring which is adapted to move them out of engagement- `withthe rack bar intermittently during the operation of the lever for lowering the rack, another spring being adapted to be moved 2G into engagement with the pawl and the detent and to overcome the first named spring for forcing the pawl and detent into engagement with the rack during the operation of the lever for elevating the rack or plunger. Other objects relate to various features of construction and arrangement which will appear more clearly hereinafter.

The nature of the invention willbe understood from the following specification taken Vwith the accompanying drawings in which one'embodiment-is illustrated. In the drawings Figure 1 shows a vertical section throughv the improved jack, illustrating a side elevation of the operating mechanism 5 for raising or lowering the rack bar or plunger; Fig. 2 shows a horizontal section taken on the line 2-2 of Fig. 1; Fig. 3 is a` view similar to Fig. 2 showing a partial side elevation of the operating mechanism with the lever elevated and one of the controlling springs rendered inoperative to permit the lowering of the rack or plunger; Fig. 4 is a ,view similar to Fig.f3 showing theposition of the parts when the lever is in its lower position; Fig. 5 shows a side elevation of the end of the lever and the'pawl and detent with their springs removed from the p standardV or casing of the jack; Fig. 6 shows a detail section taken on Vthe line 6--6 of 1924. serial No. 707,815.

Fig. 5; and Fig. 7 is a view similar to Fig. 5, showing a modification.

The frame or supporting structure of the l jack may be readily formed at small cost by stamping the principal parts thereof from sheet steel or the like. This structure comprises a base 10, of rectangular form having an annular depending iange 10a adapted to rest on the support for the jacket. The base 10 forms a support for a vertical standard or casing 11 which, like the part 10, is stamped from sheet steel or the like in one piece. The part 11 comprises two side walls 1 11 which are provided at their lower ends with transversely extending flanges 11b secured to the base 10 by means of rivets 12. The vertical side walls 11a of the standard are connected by a single integral end wall 11C. The side walls 11a are provided with inclined edges 11d at their upper endsV and an inclined top wall or cover 13 extends between these inclined edges with the ends thereof rolled to form cylindrical parts 13a adapted to be engaged by the rivets 14 whichextend between the side walls 11a. The opening is thus formed between the top wall 13 and the end wall 11c to receive the vertical plunger or rack bar 15 of the jack. This plunger is provided along one edge with rack teeth 15a and it is prevented from accidental removal from the casing or standard 11 by a transverse pin 16 which extends through an aperture in the lower part thereof with its ends loosely engaging the grooves 17 which are formed in the side walls 11a and which are closed at their upper and lower ends. In assembling the jack, the pin 1G is put in place in the plunger 15 after which the side walls 11a are bent into parallel relation to secure the rack bar in position before the standard 11 is attached to the base. The

rack bar 15 is provided at its upper end with' axle 2l extending through these side walls.

on a pin 2st which extends between the' side flanges 20c ot the lever and the detent 23 is mounted on the pin 2l which supports the lever. The upper hooked extremities 22a and 23, respectively, of the pawl and the detent are adapted to engage the teeth' l5 of the rack bar and the arms 22b and 23h, re`- spectively, of the pawl and detent, which extend below the axis of the lever are connected by a coil spring 25 having its arms or terminals 25a connected to the pins 2G which are mounted on the arms 22b and 23". The detent 23 is provided with a laterally extending hub 23c havingmounted -hereon another coil spring 27 which terminates in elongated arms 27L and 27b adapted to engage the lateral projections 22d and 23d which are Jformed on the hooked extremities oi the pawl and detent. As shown in Figs. 3, i and 5, the arms of the spring 27 are tree and have no appreciable eiiect upon thD pawl or detent so that either of these members is f permitted by the spring 27 to pass out of engagement with the raclr bar. However'the hooked extremities 22a and 33L of the pawl and the detent may be maintained in engagement with the teeth. of the raclrbar by operating a latch member 28 vvhi'ch ispivoted on one ot the pins 14 previously7 described and which is provided with a transverse flange 23 adapted to engage the upper arm 27b of the spring 27 when the latch is swung to the position illustrated in Fig.. l,

thereby causing the arms 27a and 27b to enA gage the lateral projections 22d and 23d formed on the pawl and detent, respectively; The spring 27 is or' greater strength than the spring 25 so that when the latch 2S is in the position shown in Fig. l, the etlect oi' the spring 25 isovercome by the action i the spring 27. lVhen the latch 2S is mov the position illustrated in Figs. 3l and el, the

` spring 27 is disengaged from the pawl and the detent so thatthe spring 25 is then et'- liective to bring about the necessary action of the pawl and the detent in permitting the lowering movement of the rack bar or lunffer. 'In order to maintain the pawl 22 i b i in a position in alignment with? the detent 23, a collar 29 is mountetL on `the pin 24 at one side of the pawl. In order to prevent the excessive downward movement of the lever t 20, a roller 30 .is mounted on a pin? 3l extending between the side walls 11a at a point some distance belowthe axis 2l of the lever.

When it is desired to use the jack for lifting a body, the latch 28 is moved to the position illustrated in Fig. l, thereby forcing the upper arm 27h of the spring 27 into engagement with the upper end of the: detent 23 and causing the other arm of the spring to move the' pawl 22 into engagement with the rack bar. With the pawl and detent held in engagement with the rack teeth by the arms of the spring 27, the reciprocation of the lever 20 about the axis 21 will cause the rack bar or plunger to be elevated by each upwardl movement of the pawl 22 and, after each upward movement of the rack bar, it is maintained in its elevated position by' the d'etent 23, the hooked extremity 25a' of which slides over the inclined rack teeth during the upward movement of the rack bar. When it is desi-red to lowerV the plunger or rack bar of the jack in itsl support, the latch bar 28 is moved to the position' illustrated in F igs. 3 and 4 thereby disengaging the spring 27 from thev detent 23 and' causing it to have no appreciable e-ii'ect upon. thev pawl 22. When the lever is in its upper position as il lustrated in F ig. 3, the pawl. 22 is in the po"- sitionillustrated by full lines intha-t figure andthe detent 23- is in engagement. withf' the teeth of' the rack bar, due. tothe fact that the downward movement of the pawl 222 causes the arms 253er the spring25 te be compressed with a corresponding thrust on. the arm 23p of the detent and a consequent movement ef the upper end ofl the detent into engagement with the rack bar.. As the leverV 20 is lowered about its pivot 2l', the arms ,25 of the spring 25 separate andthe pawl.v 22 is rocked about its pivot. 2a until it engages the teeth. of the rack bar and causes an upward movement of the rack' bar' suflicient to permit the disengagement or the detent 23 from the rack bar under the influence of the spring 25 it being understood that the arms. 25L of the spring 25i are spread apart beyond. thei-rlneu.- tral or relaxed positions during the downward movements of the lever so that asV the lever reaches the lower limit ofi its ,movement, the spring 25 exerts a pull on the lower arm 23 of the detent which pulls the hooked extremity 23a thereof out ofengagement with the rackk teeth. In this way the lever 2O may be reciprocated repeatedly until the rack bar 15 is lowered to the desired extent. When there is no load on the ack, the rack bar may be conveniently lowered without reciprocating the lever by inserting a finger between the side walls 11a and pressing inwardly on the arm 23a of the detent until it releases the r ack`bar.

In Fig. 7 there is illustrated a slightmodi.- li'cation in which a pawl 22k and a d'eteimtA 23k are mounted on pins engaging a lever but the axis of the spring 27 k, instead orbe-y ing coincident with the axis of the lever, is formed by a lug 33 on the detent above the member 21k on which the lever is mounted.

Although I have shown and described one form of the invention, it will be understood that it may be constructed in various other embodiments without departing from theV scope of the appended claims.

I claim:

l. A lifting jack comprising a rack, a pivotally mounted lever, an actuating pawl mounted to be actuated by said lever to move said rack bar, a holding detent pivotally mounted on said lever and adapted to engage said rack bar, a spring connecting said pawl and said detent to force them out of engagement with said rack to permit the lowering of said rack, and a second spring adapted to engage directly both said pawl and said detent to force them into engagement with said rack against the action of said first-named spring to permit the upward movement of said raclr.l

2. A lifting jack comprising a standard, a rack bar mounted for vertical movement in said standard, a lever pivotally mounted on said standard, a pawl pivoted on said lever and adapted to engage said rack bar, a detent pivoted on the axis of said pivotal mounting of said lever and adapted to engage said rack bar, said pawl and said detent having arms extending from their pivotal axes, opposite to the parts thereof which engage said rack bar, a coil spring having its extremities coni neeted to the arms of said pawl and said detent, said spring being adapted to eifect the alternate engagement and disengagement of said pawl and said detent with said rack bar to effect the lowering movement of said rack bar by the reciprocation of said lever, and a second spring of greater strength than said iirst named spring having parts adapted to engage said pawl and said detent above their pivotal axes to force the upper i extremities of said pawl and said detent into engagement with said rack bar to effect the upward movement'of said rack bar by the reciprocation of said lever.

3. A lifting jackcompiising a standard, a rack bar mounted for vertical movement in said standard, a lever pivoted on said standard, an actuating pawl pivoted on said lever and adapted to actuate said rack bar upon movement of said lever, a holding detent 1 mounted for pivotal movement about the pivotal axis of said lever and adapted to engage said rack bar, a spring carried entirely by and connecting said pawl and said detent at one side of their pivotal axes to control their engagement with said rack bar during the lowering movement of said rack bar by the reciprocation of said lever, and means comprising a second spring mounted to engage directly said pawl and said detentat the side of their pivotal axes opposite said iirst-named spring for controlling the engagement of said pawl and said detent with said rack bar during the elevation of said racli bar by the reciprocation' of said lever.

4; A lifting ack comprising a standard, a

rack bar mountedvfor vertical movement in a the lowering movement of said rack bar by a reciprocation of said lever, and a second spring of greater strength than said first named spring having parts adapted to engage said pawl and said detent above their pivotal axes to force the upper extremities of said e pawl and said detent into engagement with said rack bar to effect the upward movement of said rack bar by the reciprocation of said lever, and means for rendering said second named spring inoperative when desired.

5. A lifting jack comprising a rack, a lever. an actuating pawl, a holding detent, said pawl and said detent being each pivotally mounted on said lever to permit movement thereof when said lever is actuated, said pawl and said detent having parts at one side of their pivotal axes adapted to engage said rack, a spring supported by and connecting said pawl and said detent at the side of their pivotal axes opposite said engaging parts for con-V trolling the movement of said pawl and said detent during the lowering movement of said rack, and a second spring mounted independently of said iirst named spring and directly engaging saidpawl and said detent adjacent said engaging parts for controlling the movements of said pawl and said detent during the elevation of said rack.

6. A lifting ack comprising a rack, a pivotally7 mounted lever, an actuating pawl pivoted on said lever to, move said rack bar, a holding detent pivotally mounted for movement about the pivotal axis of said lever and adapted to engage said rack bar, a spring connecting said pawl and said detent to force izo them alternately out of engagement with said rack to permit the lowering of said rack, a second spring adapted to engage directly both said pawl and said detent to force them into engagement with said rack against the action rack har :mounted for ver-tical movement in seid standard, ay lever pivoted on said standard, an actuating paWl pivoted on said lever and adapted to engage said rack bar, a holding `detent pivoted on u relatively stationary axis :and adapted to engage said rack bar, 'a spring supported on and connecting the ends of said ps Wl und said detent at lthe side 'of their pivotal Iaires opposite their rack-"engaging portions for controlling their engagement With/said rack bar during the lowering move- .ment yoi the mok bar by the reeiprooation of said lever, u second spring mounted about the pivotal axis of said lever and having a pair of free extremities adapted to engage the rack-engaging portions of seid paWl end said detent, respectively, and ineens for moving said free 4extremities 'of said Vlest-named spring into and out of engagement with said :pawl yand said detent.y '1

`ELON J. VAN FLEET. 

